Workpiece holding frame

ABSTRACT

A workpiece holding frame includes: a main body having a frame side; and a holding piece directly attracted by magnetic force towards the frame side. A sheet-like workpiece is sandwiched and held between the frame side and the holding piece to make the workpiece stretched taut at a lower surface of the holding frame. The workpiece is subjected to selectively both of printing and embroidery processes without having to change the resulting stretched-taut state. The holding piece has a groove for accommodating therein a permanent magnet. The frame side includes a flat portion and a rib extending perpendicularly along an inner edge thereof, and the holding piece is disposed so as to be accommodated in a space of the frame side which is formed by the flat portion and the rib. The workpiece is bent in contact with an end edge of the rib to be is stretched taut.

BACKGROUND

The present invention relates generally to frames for holding a workpiece, such as a fabric, in a stretched-taut state, and more particularly to a workpiece holding frame detachably attachable to selectively both of a printing apparatus for performing printing on a workpiece and an embroidery sewing machine for performing embroidery on the workpiece while keeping the same workpiece held thereon.

Among a wide variety of embroidery products made today are ones having a combination of printed and embroidered patterns. To make such a product having a combination of printed and embroidered patterns, printing of a desired pattern is performed on a fabric (workpiece) by means of a printing apparatus, and then embroidery of a desired pattern is performed on the fabric by means of an embroidery sewing machine. The printing apparatus, which may comprise for example a printer for use with a personal computer or the like, includes a print head movable in an X direction, and a transfer device for moving, in a Y direction, a member, called “platen”, capable of holding a workpiece, such as a T-shirt, in a stretched-taut state. The platen having the workpiece held thereon is moved in the Y direction by the transfer device on the basis of image data while the print head is moved in the X direction, so that desired printing is performed on the workpiece.

On the other hand, the embroidery sewing machine includes a machine head having a sewing needle driven reciprocatively in a vertical (up-down) direction, and a frame transfer mechanism for moving the embroidery frame in the X and Y directions. The embroidery frame, as conventionally known, includes an outer frame member and an inner frame member, and a workpiece is sandwiched and held stretched taut between the inner peripheral surface of the outer frame member and the outer peripheral surface of the inner frame member. Such an embroidery frame having the workpiece held thereon in a stretched-taut state is set onto the frame transfer mechanism and then moved in the X and Y directions, while the sewing needle of the machine head is driven in the vertical direction to perform embroidery onto the workpiece.

Namely, a typical example of the conventionally-known technique is arranged in such a manner that, when performing printing on the workpiece, the workpiece is held on the platen of the printing apparatus in a stretched-taut state, and that, when performing embroidery on the workpiece, the workpiece is held on the embroidery frame of the embroidery sewing machine in a stretched-taut state. Namely, with the typical conventionally-known technique, it is necessary to perform operations for attaching and detaching the workpiece to and from the platen and then attaching and detaching the workpiece to and from the embroidery frame. Thus, with the conventionally-known technique, much time and labor would be required, and positional alignment between a print pattern and an embroidery pattern tends to be difficult. Therefore, it has heretofore been contemplated to make the embroidery frame attachable to the printing apparatus so as to attach the embroidery frame to selectively both of the printing apparatus and the embroidery sewing machine with the workpiece kept held on the embroidery frame. However, generally, the embroidery frame sandwiches the workpiece between the inner peripheral surface of the outer frame member and the outer peripheral surface of the inner frame member, and the workpiece is stretched taut at generally the same height as the lower surfaces of the outer and inner frame members. Thus, if the embroidery frame is attached as-is to the printing apparatus, the print head would be located at a height over the workpiece where it interferes with the inner frame member, i.e. it is interfered with by the inner frame member. Therefore, the print head is allowed to move only within a range where it does not interfere with, or it is not interfered with by, the inner frame member, i.e. within a limited range in the neighborhood of the middle of the frame. In such a case, however, movement of the print head is limited because the print head has a great horizontal width and depth, which would result in a considerably reduced printable range. An improved embroidery frame capable of avoiding such an inconvenience is disclosed in Japanese Patent Application Laid-open No. 2005-036330 (hereinafter referred to as “Patent Document 1”).

In the embroidery frame disclosed in Patent Document 1, at the time of embroidering, a workpiece is sandwiched between the outer frame member and the inner frame member and stretched taut at generally the same height as the lower surfaces of the outer and inner frame members, as in the aforementioned conventionally-known technique. At the time of printing, on the other hand, an auxiliary frame is inserted from below along the inner peripheral surface of the inner frame member, more specifically into a space defined by the inner peripheral surface of the inner frame member, so that the workpiece is stretched taut at generally the same height as the upper surfaces of the outer and inner frame members. Because the workpiece is stretched taut at generally the same height as the upper surfaces of the outer and inner frame members at the time of printing, the print head does not interfere with the inner frame member, and thus, the printable range would not decrease.

Incidentally, in many of embroidery products comprising a combination of printed and embroidered patterns, embroidery is performed after printing in such a manner that an embroidery is superposed on a part of a printed pattern. The embroidery frame disclosed in Patent Document 1 first holds a workpiece in a stretched-taut state by means of outer and inner frame members. Where printing is to be performed before embroidery, an auxiliary frame member is pressed or inserted from below along the inner periphery of the inner frame member (more specifically, into the space defined by the inner periphery of the inner frame member), and then the workpiece is stretched taut at generally the same height as the upper surfaces of the outer and inner frame members. The embroidery frame placed in that state is set onto a printing apparatus so that printing is performed on the workpiece. After completion of the printing, the embroidery frame is removed from the printing apparatus, and the auxiliary frame member is detached from the embroidery frame. Then, the workpiece is placed in a state where the workpiece is stretched taut at generally the same height as the lower surfaces of the outer and inner frame members. The embroidery frame placed in this state is set onto an embroidery sewing machine so that embroidery is performed on the workpiece.

With the embroidery frame disclosed in above-described Patent Document 1, where the auxiliary frame member is pressed into the space defined by the inner periphery of the inner frame member when printing is performed, the workpiece can be held stretched with increased tightness or tautness at the time of printing. Thus, when embroidery is to be performed subsequently after removal of the auxiliary frame member, the tautness of the workpiece would slack, producing unwanted slackness or looseness in the workpiece. As a consequence, quality of an embroidery made in the aforementioned manner would deteriorate.

SUMMARY OF THE INVENTION

In view of the foregoing prior art problems, it is an object of the present invention to provide a workpiece holding frame with an improved structure which can subject a workpiece to selectively both of printing and embroidery processes without having to change the stretched-taut state of the workpiece on the holding frame.

In order to accomplish the above-mentioned object, the present invention provides an improved workpiece holding frame which holds a workpiece such that the workpiece can be subjected to selectively both of printing and embroidery processes, and which comprises: a holding frame main body having at least one frame side; and at least one holding piece directly attracted by magnetic force towards the frame side of the holding frame main body, wherein the workpiece in the form of a sheet is sandwiched and held between the frame side and the holding piece, causing the workpiece to be in a stretched taut at a lower surface of the holding frame, thereby allowing the workpiece to be subjected to selectively both of printing and embroidery processes without having to change the stretched-taut state.

According to the present invention, the holding piece that cooperates functionally with the holding frame main body to sandwich a workpiece therebetween is constructed such that it is directly attracted by magnetic force towards the frame side of the holding frame main body. Accordingly, the overall structure of holding frame main body can be made low profile. Therefore, in a state where the holding frame is configured such that a workpiece in the form of a sheet is sandwiched and held between the frame side and the holding piece and the workpiece is stretched taut at the lower surface of the holding frame, the distance between the lower and upper surfaces of the holding frame becomes relatively small, and as a result, if the workpiece is subjected to a printing process without changing the stretched-taut state, an interference of the upper surface height of the holding frame with the printing action can be kept to the minimum as much as possible. Consequently, according to the present invention, a workpiece can be subjected to selectively both of printing and embroidery processes without having to change the stretched-taut state of the workpiece on the holding frame. Further, a deterioration of the quality of embroidery due to a change in the degree of tautness can be eliminated.

According to an embodiment, a permanent magnet is provided on at least one of the frame side of the holding frame main body and the holding piece, and the magnetic force of the permanent magnet directly penetrates the workpiece sandwiched between the frame side of the holding frame main body and the holding piece such that it acts between the frame side of the holding frame main body and the holding piece. According to such a structure, in the case where the frame side of the holding frame main body and the holding piece are vertically superposed, the thickness in the vertical direction is made relatively low profile and the area of the superposed portion in the lateral direction is made relatively large, so as to ensure sufficient attractive force (that is, a thin plate magnet is used), which is fit for making the overall holding frame structure low profile.

In the embodiment, the frame side of the holding frame main body may include a flat portion and a rib extending approximately perpendicularly along an inner edge of the flat portion, and the holding piece may be disposed so as to be accommodated in a space defined by the frame sides, which is formed by the flat portion and the rib, and the workpiece sandwiched and held between the frame side and the holding piece is stretched taut on the holding frame main body in a state bent at an end edge of the rib and in contact therewith. With such a simplified construction, the workpiece can be stretched taut, and the simplified overall structure is suitable for making the overall structure of the holding frame low profile.

The following will describe embodiments of the present invention, but it should be appreciated that the present invention is not limited to the described embodiments and various modifications of the invention are possible without departing from the basic principles. The scope of the present invention is therefore to be determined solely by the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Certain preferred embodiments of the present invention will hereinafter be described in detail, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 is a plan view of an embodiment of a holding frame main body of a workpiece holding frame of the present invention as seen from an upper surface side;

FIG. 2 is a bottom view of the holding frame main body shown in FIG. 1 as seen from a lower surface side;

FIG. 3 is a perspective view of a holding piece of the holding frame;

FIG. 4 is a perspective view of the holding piece as seen from a lower surface side;

FIG. 5 is an exploded perspective view of the holding frame main body for illustrating the state in which a workpiece and an interlining are held on the holding frame main body via the holding piece, as seen from the lower surface side of the holding frame main body;

FIG. 6 is a rear view showing the state in which a workpiece and an interlining are held on the holding frame main body via the holding piece as seen from the lower surface side;

FIG. 7 is an enlarged sectional view taken at line A-A of FIG. 6;

FIG. 8 is a plan view of the state shown in FIG. 6, as seen from the upper surface side;

FIG. 9 is a perspective view of the state shown in FIG. 8; and

FIG. 10 is a perspective view of an example of a single-head type embroidery sewing machine to which the preferred embodiment of the holding frame may be applied.

DETAILED DESCRIPTION

A holding frame 6 according to the present invention is configured by a combination of a holding frame main body 1 shown in FIGS. 1 and 2 and a holding piece 3 shown in FIGS. 3 and 4. The holding frame main body 1 is configured by a thin plate made of magnetic materials such as a steel plate, and is formed by joining, by means of welding or the like, respective frame sides 1 a and 1 a′ on right and left sides and respective frame sides 1 b and 1 b′ on upper and lower sides into a rectangular shape. On opposing inner edges of the respective frame sides 1 a, 1 a′, 1 b and 1 b′, a rib 2 bent toward a bottom side at a predetermined width from an end of the inner edge is formed for each frame side, as shown in FIGS. 2 and 5. A height of the rib 2 is, for example, 5 mm or less. Attaching arms 1 c are formed respectively on outer sides of the right and left frame sides 1 a, 1 a′. The attaching arms 1 c are provided for attaching the holding frame main body 1 to a frame driving portion (not shown) of an embroidery machine.

An explanation will now be given for the holding piece 3 with reference to FIGS. 3 and 4. The holding piece 3 is provided for sandwiching a workpiece 7 in the form of a sheet, such as a fabric, and an interlining 8 between the holding piece 3 and the holding frame main body 1 by magnetic force, such that the workpiece 7 in the form of a sheet and the interlining 8 are held on the holding frame main body 1. As shown in the figures, one holding piece 3, in a form of a narrow rectilinear shape, is made of magnetic materials such as a steel plate having a predetermined thickness, and has a predetermined rigidity and has substantially no flexibility. The predetermined thickness is, for example, preferably generally equivalent to the height of the rib 2 of the holding frame main body 1. A width of one holding piece 3 is generally the same as widths of the right and left frame sides 1 a and/or upper and lower frame sides 1 b of the holding frame main body 1, and a length of the holding piece 3 is generally the same as lengths of the respective frame sides 1 a and/or 1 b of the holding frame main body 1. Preferably, a plurality of holding pieces 3 are used. For example, holding pieces 3 (total of four) are used in correspondence with the respective frame sides 1 a and 1 b of the holding frame main body 1.

On a back side of the holding piece 3, a groove 3 a having a constant width is formed and extends at a center portion in a width direction of the holding piece 3 along a length direction thereof. Permanent magnets (neodymium magnets, for example) 5 in the form of plates are embedded in the groove 3 a at arbitrary intervals. The holding piece 3 is directly attracted by the magnetic force of the permanent magnets 5 so as to be stuck detachably to the frame sides 1 a and 1 b of the holding frame 6. Further, a plurality of permanent magnet pieces do not necessarily need to be disposed at intervals, but instead, a wider space may be provided between the permanent magnet pieces or the permanent magnet pieces may be disposed to be in contact with each other, depending on the magnitude of attractive force thereof to the holding frame main body 1. Accordingly, the holding frame 6 is configured by including the holding frame main body 1 and the holding piece 3 attracted by the magnetic force so as to be stuck detachably to the respective frame sides 1 a, 1 a′, 1 b and 1 b′ of the holding frame main body 1. As described later, the workpiece 7 (and the interlining 8) is sandwiched and held stretched taut between the respective frame sides 1 a, 1 a′, 1 b and 1 b′ of the holding frame 6 and the holding piece 3. Such a configuration allows the magnetic force of the permanent magnets 5 to act between the respective frame sides 1 a, 1 a′, 1 b and 1 b′ of the holding frame 6 and the holding piece 3, the magnetic force directly penetrating the workpiece 7 (and the interlining 8) sandwiched therebetween. Further, attractive force due to the magnetic force of the permanent magnets 5 acts in a vertical direction (in a height direction). As a result, the holding frame 6 adopting a holding structure using such permanent magnets 5 in the form of plates can be configured such that the thickness thereof would be thin (that is, the height would be low) (for example, referring to FIG. 7, approximately 5 mm high, which is the height of the rib 2). Such a low profile holding frame 6 is extremely advantageous because interference with a print head of a printer (not shown) does not occur.

The permanent magnets 5 may be fixed by adhesive or the like when disposed in the groove 3 a of the holding piece 3, or the permanent magnets 5 may be semi-fixed to the holding piece 3 made of a magnetic body by magnetic force of its own, instead of being fixed by adhesive or the like. Further, when fixing the permanent magnets 5 in the groove 3 a of the holding piece 3 by adhesive or the like, the holding piece 3 may be made of a non-magnetic material. Also, as a modified example, the permanent magnets 5 may be provided on the side of the respective frame sides 1 a and 1 b of the holding frame main body 1 (for example, being fixed by adhesive or the like), and in such a case, the holding frame main body 1 may be made of a non-magnetic material, the holding piece 3 being made of a magnetic body. As another modified example, the holding piece 3 itself may be configured by a permanent magnet in the form of a plate.

Procedures for setting the workpiece 7 and the interlining 8 on the holding frame 6 will now be described with reference to FIG. 5.

(1) First, the holding frame main body 1 is reversed (the back side, or the lower surface side shall be up), and the workpiece 7 and the interlining 8 are put over the holding frame main body 1 in this order. (2) Next, with the workpiece 7 and the interlining 8 being in sufficiently stretched taut states, the holding pieces 3 are set to the respective frame sides 1 a and 1 b of the holding frame main body 1 from over the interlining 8. Accordingly, the respective holding pieces 3 are strongly attracted to the respective frame sides 1 a and 1 b of the holding frame main body 1 by the magnetic force of the permanent magnet plates, and the workpiece 7 and the interlining 8 are held surely stretched taut between the holding piece 3 and the holding frame main body 1.

An example of specific procedures for setting the holding piece 3 in step (2) above will now be described with reference to FIG. 6.

(2-1) In FIG. 6, a holding piece to be set first is 3-1, for example. A tip 3-1 a of the holding piece 3-1 is pressed against an abutting position 2 a of the rib 2, and then the holding piece 3-1 is inclined so as to be stuck on the holding frame main body 1. (2-2) Next, a tip of a holding piece 3-2 to be set second is made to abut against an end 3-1 b (a portion protruding from an abutting position 2 b of the rib 2) of the holding piece 3-1 so as to be stuck on the holding frame main body 1 in the same manner as aforementioned step (2-1). (2-3) Similarly, a holding piece 3-3 to be set third and a holding piece 3-4 to be set fourth are stuck on the holding frame main body 1.

Referring to FIG. 7, which is an enlarged sectional view taken at line A-A of FIG. 6, explanation will now be given for the state in which the workpiece 7 and the interlining 8 are attached to the holding frame main body 1. According to the figure, the workpiece 7 and the interlining 8 are sandwiched and held between the holding frame main body 1 and the holding piece 3 by the magnetic force of the permanent magnet plates 5, and the workpiece 7 and the interlining 8 are in a state bent at a right angle by an end edge 2 e of the rib 2. Accordingly, the tension of holding the workpiece 7 and the interlining 8 in a stretched-taut state does not decrease. Further, the tension acting in the space surrounded by the frame can be increased by pulling the workpiece 7 and the interlining 8 in an arrow B direction of FIG. 7 when the workpiece 7 and the interlining 8 are set. At this time, the holding piece 3 is not displaced toward the outer side.

Further, FIG. 7 shows a state where the holding frame 6 is turned upside down. That is, the top side in this sectional view represents the lower surface (back surface) side of the holding frame 6, and the bottom side in this sectional view represents the upper surface side of the holding frame 6. FIG. 8 is a top view (plan view) of the state where the workpiece 7 and the interlining 8 are set on the holding frame main body 1, which is a view from the upper surface side of the holding frame 6 in FIG. 6. FIG. 9 is a perspective view of a state where the workpiece 7 and the interlining 8 are set on the holding frame main body 1, as seen from the upper surface side. As is evident from FIG. 7, the holding frame 6 according to the present embodiment is configured such that the workpiece 7 (and the interlining 8) is stretched taut at the lower surface thereof. Further, as described later, the workpiece 7 (and the interlining 8) can be subjected to selectively both of printing and embroidery processes without changing the stretched-taut state of the workpiece 7 (and the interlining 8) in the holding frame 6. That is, printing and embroidery is performed on the workpiece 7 (and the interlining 8) from the upper surface side of the holding frame 6 in the state where the workpiece 7 (and the interlining 8) stretched taut on the holding frame 6 is located on the lower surface thereof. Accordingly, the lower surface of the workpiece 7 (interlining 8) is supported by the platen (not shown) during printing and is supported by a needle 12 (FIG. 10) during embroidery, thereby allowing smooth printing and embroidery. Further, while the upper surface of the holding frame 6 is apart from the lower surface by nearly 5 mm, the distance is only slight, and therefore does not hinder printing.

As shown in FIG. 7, or FIG. 2 or FIG. 5, the respective sides 1 a, 1 a′, 1 b and 1 b′ of the holding frame main body 1 have, at the lower surface sides thereof, a flat portion and the rib 2 extending approximately perpendicularly along an inner edge of the flat portion. The holding piece 3 is disposed such that it is accommodated in a space defined by the frame sides, which is formed by the rib 2 and the flat portion on the lower surface side of the frame sides 1 a, 1 a′, 1 b and 1 b′. The workpiece 7 (and the interlining 8) sandwiched and held between the frame sides 1 a, 1 a′, 1 b and 1 b′ and the holding piece 3 is stretched taut at the lower surface of the holding frame main body 1 in such a manner that the workpiece 7 (together with the interlining 8) is bent in a condition where the workpiece 7 (together with the interlining 8) is in contact with the end edge (lower end edge) of the rib 2. Here, the rib 2 does not necessarily have to be bent perfectly perpendicularly, but instead, it may be bent in an arbitrary angle other than 90 degrees.

When removing the workpiece 7 and the interlining 8 from the holding frame 6, the holding piece 3 is stripped away from the holding frame main body 1. In explanation of the procedures therefor, referring to FIG. 6 and taking the holding piece 3-1 as an example, the holding piece 3-1 can be easily stripped off by lifting an end 3-1 e thereof from the bottom side with a finger. As is evident from the figure, because the length of the holding piece 3-1 is set such that the end 3-1 e of the holding piece 3-1 protrudes a little from the end edge of the holding frame main body 1, the holding piece can be stripped off easily, as described above, using the protruded portion as a grip.

Next, an example of printing and/or embroidery procedures will be described. As shown in FIG. 9, in the case of first performing printing in a state where the workpiece 7 and the interlining 8 are set on the holding frame main body 1, the holding frame 6 to which the workpiece 7 and the interlining 8 are set is placed on a platen (not shown) in the form of a plate of a printer (not shown) to perform printing. The printer (not shown) may be of a commonly known type capable of printing arbitrary graphic, characters, and the like by driving the platen (not shown) in the form of a plate on a two-dimensional plane in X and Y directions. In the case of performing embroidery to the workpiece 7 on the holding frame 6 that has gone through printing of arbitrary graphic and pattern, the holding frame 6 can be set to an embroidery machine as is to perform a desired embroidery. For example, by connecting the attaching arms 1 c and 1 c provided on selectively both sides of the holding frame main body 1 to supporting arms 11 and 11 of an embroidery machine 10 as shown in FIG. 10, the holding frame 6 can be set to a embroidery frame driving mechanism of the embroidery machine 10. The embroidery machine 10 can be activated after setting the holding frame 6 to the embroidery frame driving mechanism of the embroidery machine 10 as thus. Further, the sequence of performing printing and embroidery processes may be in any order

Further, when setting the holding frame 6 to the embroidery machine 10 for performing embroidery, a height position of a back surface of the interlining 8 (or a height position of a back surface of the workpiece 7) in FIG. 9 needs to be generally equal to that of an upper surface of a needle plate 12 (FIG. 10) of the embroidery machine 10. To do so, the supporting arm 11 of the embroidery machine 10 can be configured to match the structure of the holding frame 6 according to the present embodiment such that the height position of the back surface of the interlining 8 (or the height position of the back surface of the workpiece 7) set on the holding frame 6 is generally equal to that of the upper surface of the needle plate 12. For example, in the case where an existing supporting arm (11) is provided on an existing embroidery machine 10, the existing supporting arm (11) may be replaced with a dedicated supporting arm 11 configured so as to match the structure of the holding frame 6 according to the present embodiment, or instead of replacing the supporting arm (11), an arbitrary height raising member (an attachment for assisting attachment) may be provided at an attaching portion at a tip of the existing supporting arm (11).

According to the present embodiment, when the holding frame 6 is placed on the platen of the printer for printing, the workpiece 7 is close enough to the printer nozzle since the height of the rib 2 is only about 5 mm, and therefore a sharp printing can be performed as well as a printing on a wide range (entire region shown by the dashed line in FIG. 6) without interfering with the movement of the print head.

According to the present invention, when switching from a printing process to an embroidery process, or from an embroidery process to a printing process, once the workpiece 7 and the interlining 8 are held on the holding frame main body 1, nothing more needs to be done to the holding state. Accordingly, it is possible to perform high-quality processing without a displacement occurring between the printing process and the embroidery process.

Further, the present invention is not limited to a rectangular holding frame (6), but is also applicable to a holding frame having one or more curved frame sides or a round frame side. In such a case, a plurality of holding pieces (3) having curves matching curvatures of the holding frame (6) may be used in combination. Whether using rectilinear or curved holding pieces 3, the plurality of holding pieces 3 do not necessarily have to be configured so as to cover the entire length of the curved (or round) frame sides of the holding frame 6, but instead, the holding pieces 3 may be configured to sandwich the workpiece 7 between the frame side and the holding piece 3 at some dispersive locations.

This application is based on, and claims priority to, Japanese Utility Model Application No. 2013-005098 filed on Sep. 3, 2013. The disclosure of the priority application, in its entirety, including the drawings, claims, and the specification thereof, is incorporated herein by reference. 

What is claimed is:
 1. A workpiece holding frame which holds a workpiece such that the workpiece can be subjected to selectively both of printing and embroidery processes, the workpiece holding frame comprising: a holding frame main body having at least one frame side; and at least one holding piece directly attracted by magnetic force towards the frame side of the holding frame main body, wherein the workpiece in the form of a sheet is sandwiched and held between the frame side and the holding piece, causing the workpiece to be in a stretched taut state at a lower surface of the holding frame, thereby allowing the workpiece to be subjected to selectively both of printing and embroidery processes without having to change the stretched-taut state.
 2. The workpiece holding frame as claimed in claim 1, wherein a permanent magnet is provided on at least one of the frame side of the holding frame main body and the holding piece, and the magnetic force of the permanent magnet directly penetrates the workpiece sandwiched between the frame side of the holding frame main body and the holding piece so as to act therebetween.
 3. The workpiece holding frame as claimed in claim 2, wherein the holding piece has a groove for accommodating therein the permanent magnet.
 4. The workpiece holding frame as claimed in claim 1, wherein the frame side of said holding frame main body includes a flat portion and a rib extending approximately perpendicularly along an inner edge of the flat portion, the holding piece is disposed so as to be accommodated in a space of the frame side which is formed by the flat portion and the rib, and the workpiece sandwiched and held between the frame side and the holding piece is stretched taut on the holding frame main body in such manner that the workpiece is bent in a condition where the workpiece is in contact with an end edge of the rib.
 5. The workpiece holding frame as claimed in claim 4, wherein a height of the rib is 5 mm or less. 